Ventajas
Lockheed is a relatively traditional company (neither good nor bad, depends on what you prefer.) Career growth is fairly predictable. Huge company with lots of opportunity for moving around - be it to different departments or different cities. Good pay, great benefits, great job security. You could easily be a lifer here if that's what you wanted. Really easy to balance work and home life. We had 9/80 (9 hour days with every other friday off and flex-time) plus about 10-days plant shut-down at Christmas on top of the regular 3 weeks of vacation for entry-level ee's. I was able to travel a ton while I worked here.
Desventajas
The general demo is middle-aged, white, republican males. You generally have to be able to appeal to this demographic to get ahead. I also witnessed TONS of less-than-kosher employee activity and you only got fired if you broke the law. They don't do much in the way of perks. Campus and offices are fairly drab. Old-style cubicles, entire floors without windows. Cafeteria with over-priced food. Work, especially for lower level employees, can be mundane and lacks any room for strategic thinking, creativity etc. You are doing the exact same work that all other employees in your function and level are doing.